Telephone system



Patented Mar. 9, 1937 `:UNITED STATES PATENT OFFICE 18 Claims.

My invention more particularly relates to visual types ofA signals and circuits associated therewith and with a telephone system, the general arrangements being similar to those described and illustrated in my pending application Serial No. 670,715 which was filed in the Patent Oilice on or about May l2, 1933, of which this present application is a continuation in part.

In many instances, quietness must be maintained with an exception, however, extended to signaling and alarm devices. My invention, therefore, has for a first object the provision of a signaling device which overcomes the inherent disadvantages of audible signaling devices and further provides a silent alarm which is equally as efficacious in many instances as audible signaling devices and more so in others.

Another object of my invention resides in the provision of means forproducing a predetermined change in the normal operating characteristics of an incandescent lamp to signal a person within the visual range thereof. A further object lies in the provision of the above mentioned means together with an automatic control circuit for an incandescent lamp which is normally manually controlled for illuminating purposes whereby an intermittent illumination thereof may be elected irrespective of the operating position of the manual control for said lamp.

It will be noted, as hereinafter more specifically pointed out, that my invention contemplates the association with a telephone signaling circuit of a lighting circuit or separate circuit which relies on a source of power other than that feeding the signaling circuit. In such cases where an independent power supply is relied upon, it is most desirable to provide for and insure continuity of service so that one type of signal or another will be given. For example, the power may fail in the lighting circuit which is associated with the signaling circuit or the incandescent lamp which is used for signaling purposes may be either removed or burned out.

Under such circumstances, obviously, no visual signal would appear upon an operation of said signaling circuit.

A still further object of my invention, therefore, resides in the provision of an associated electric lighting circuit and a signaling circuit arranged normally to produce a visual signal upon an operation of the signaling circuit and automatically to sound an audible signal in the event of failure of operation vof said visual signal.

With these and other objects in view, my invention includes the novel elements, combinations and arrangements thereof described below and illustrated in the accompanying drawing in which- Fig. 1 is a wiring diagram of a circuit employed in one embodiment of my invention;

Fig. 2 is a wiring diagram of-a circuit employed in another embodiment' thereof;A and Fig. 3 is a fragmentary wiring diagram illustrating a, further automatic control means and its adaptation to my electrical circuits.

' Like reference characters indicate like parts throughout the drawing.

In the drawing, I have illustrated preferred embodiments of my invention wherein a signaling circuit and an electric lighting circuit are associated through suitable electrical means to predeterminately operate an incandescent lamp in response to an energization of said signaling circuit. By the use of the term energization, I mean to imply the presence of a current impulse or series of current impulses in the signaling circuit which would normally serve to operate an audible signaling device. In the drawing, the signaling circuit is diagrammatically represented as the subscribers station end of a telephone circuit.

Referring to Fig. l, an incandescent lamp I is included in a normal electric lighting circuit comprising the two legs 2 and 3 and optionally a switch 4 which may be of the usual type embodied lamp sockets. A third leg 5 completes the lamp circuit and serves to connect from the lamp side of the switch 4 to one terminal of a three pronged plug, the legs 2 and 3 being connected to the other two terminals thereof. The plug and socket therefor, illustrated at 6, provides a readily accessible connection for the incandescent lamp I which may be used as a reading light or for any other desired purpose. Obviously, this plug and socket is purely an optional element to lend flexibility to my device and forms no part of this present invention. Hence, for clearness, I have designated the respective conductors leading both to the socket and to the plug by the same reference characters, that is, the numerals 2, 3 and 5.

A currentintermitting device indicated generally at 1 is interposed in the leg 5 of the lamp circuit. It is to be understood that though I have shown a speciiic form of current intermitting device, I do not wish to be limited thereto but merely illustrate thereby an example of the means which I employ to obtain a desired operation of my device. The current intermitting device shown comprises a bimetallic element 8 one end of which is secured to a terminal block 9, the other end thereof being free to move and bearing a contact I0. A wire of suitable ohrnic resistance is coiled about the bimetallic element as at II. A second terminal block I2 bears a contact I3 with which the contact I0 is adapted to contact when the bimetallic element 8 is warped due to the heat developed and radiated return leg 3 of the lamp circuit.

by the resistance coil II. It will be noted that the contacts I0 and I3 are normally spaced from each other, but that the resistance wire or coil I I is connected between the Contact I3 and the terminal block 9. Furthermore, the terminal blocks 9 and I2 are interposed in the leg 5 of the lamp circuit. That is to say, normally, the resistance coil II is connected in series in the circuit. Hence,` when current flows through the resistance wire it will generate andradiate suicient heat to cause the bimetallic element 8 to warp towards the terminal block I2, whereupon the contacts I0 and I3 will touch, causing the resistance element II to be shunted by the bimetallic element itself. A closed circuit will be maintained between the terminal blocks 9 and I2 until contacts IU and I3 are drawn apart due to the cooling and retraction of the bimetallic element towards its normal position.

I have provided means comprising a relay I4 which is adapted to be operated alternatively to close the normal lighting circuit to the lamp or establish a closed circuit through the current intermitting device, incandescent lamp and further associated mechanisms. The relay I4 is illustrated as comprising a double armature to indicate. that two entirely independent circuits may be established thereby. Obviously, a single armature, bearing severally insulated contacts, would be entirely satisfactory. In the normal, unenergized position of the relay, as illustrated, one conducting segment I5 of the armature rests in contact with one terminal I6 of the relay to which is connected the leg 2 of the lamp circuit. The conducting segment I5 is connected through the conductors I1 and I8 to one side I9 of the lighting service mains I9 and 20. The leg 3 which forms the common return in the lamp circuit completes the normal lighting circuit to the incandescent lamp I. ergized due to the operation of means, hereinafter described, which is associated therewith and with the 'signaling circuit, the armature is picked up, thereby breaking the circuit through thesegment I5 and terminal I6 and establishing an independent circuit through the conducting segment 2i of the armature which is held by the relay in contact with the terminal 22 thereof. The third leg 5 of the lamp circuit, which includes the current intermitting device 1, is connected to the terminal 22 of the relay I4. The segment 2I of the armature is connected, first through the conductor 23, which has included therein a thermostatic switch 24 and a manually operable reset Vswitch 25, and thence through the conductor I8 to one leg I9 of the service mains. It is to be understood that the service mains I9 and 20 are connected to a suitable source of supply, not illustrated.

The coil of the relay I4 is connected to maintain a current ow therethrough when the armature has been picked up. This connection is accomplished through a conductor 26 which connects one end of the coil to the leg 5 or terminal 22 of the relay and a conductor 21 which connects the other end of theY coil to the common Hence the relay I4 will automatically maintain a circuit through the leg 5 to the incandescentlamp after an initial energization thereof.

The thermostatic switch 24 comprises a bimetallic element interposed in series in the conductor 23 and normally forming a path for the flow of current therethrough. After a predetermined interval of time, heat,"generated by the When the relay I4 is enpassage of current through said element, causes the same to warp and open the' circuit associated therewith.

The switch 25 which in its normal position is closed is additionally interposed in series with switch 24 in conductor 23 to provide means whereby a person responding to the visual signal may reset the device, that is to say switch 25 serves to open the circuit through the conductor 23 and relay I4 so that the armature thereof will return to its normal position and re-establish the normal lighting circuit to the incandescent lamp.

A signaling circuit, herein diagrammatically represented as a subscribers station, comprises the trunk lines 28 and 29, subscribers set 30 and annunciator or bell 3|.

A double contact switch 32 is interposed in the signaling circuit whereby either the visual or audible signaling means may be selected and associated with the signaling circuit. In one position, the switch 32 connects the bell 3I in the signaling circuit, while in its alternative position, the coil of the relay 33 is connected through the conductors 34 and 35 to the trunks 28 and 29. When the relay 33 is energized a current carrying segment of its armature 36 contacts with terminal 31 of the relay thereby establishing one leg of a circuit, to wit: conductor 38 which connects the coil of relay I4 to terminal 31 of the relay 33, the armature 36 thereof, conductor 39 which extends from the armature to conductor 23, and thence to one side I9 of the service mains I9 and 20. The other leg of the circuit established by the relay 33 comprises the conductor 21 which connects the other side of the coil of relay I4 to the common return leg 3 oi.' the lamp circuit.

The operation of the above described circuit is as follows. Assuming that switch 32 is in the position wherein the relay 33 is connected in the signaling circuit, an energization or flow of current through said circuit causes the armature of the relay 33 to be picked up and contact with the terminal 31 thereof. This establishes a circuit through the coil of relay I4 as hereinbefore described. When, however, the current in the signaling circuit is out off and relay 33 becomes unenergized, relay I4 automatically maintains itself in the circuit initially established therethrough by the operation of relay 33. The

automatic operation is effected through the medium of the conductor 26. After the armature I4 is attracted by the pole piece of the relay I4 and contacts with the terminal 22 thereof, conductor 26 serves to feed current back through the coil of the relay from the circuit established through its armature. Hence only a limited operation of the signaling circuit is necessary to effect an operation of my visual signaling device for a much greater period of time.

. The relay I4 normally serves to establish the normal electric lighting circuit to the incandescent lamp I as hereinbefore described. When, however, it is energized through an operation of relay 33, the normal lighting circuit is interrupted and a circuit is established to said lamp through conductors which include the current intermitting device 1, thermostatic switch 24 and reset switch 25. It will be remembered under all conditions that the leg 3 forms the common return leg of the lamp circuit.

From the foregoing it will be apparent that the incandescent lamp employed as a means for emitting a visual signal may normally be used as a. reading light or for any other illuminating puremission of one type of signal or another.

pose. Furthermore, the visual signal will appear irrespective of the position of switch 4. For example, assuming that switch 4 is closed and lamp I illuminated, an energizatio-n of the signal circuit will operate relay 33 and in turn relay I4 to cut out leg 2 of the normal lighting circuit, interpose leg 5 and establish the lamp signaling circuit. Hence an intermittent illumination of the lamp will occur though the lamp, at the time of energization of said signaling circuit, was being used for illuminating purposes.

The thermostatic switch 24 which is in circuit with the current intermitting device 1 automatically limits lthe time interval of operation of the iamp signaling circuit. Switch 25 provides a manual means for accomplishing the same result as switch 24, the latter being intended, to operate only in the event a signal is not answered and switch 25 opened.

Furthermore, it is to be understood that I do not wish to limit my lamp signaling circuit to a circuit comprising a current intermitting device as illustrated, but may rely on an operation of a relay such as relay I4 to effect a change in the normal operating characteristics of the lamp circuit whereby a visual signal is obtained.

In the above described circuit illustrated in Fig. l of the drawing, it will be noted that the operation of my signaling system is conditioned on two things, a substantially continuous power supply to the service mains I9 and 20 and nonfailure of the incandescent lamp. In Fig. 2 I have diagrammatically represented a device which eliminates the above conditions and insures an This device, which is a preferred modification of my invention, comprises substantially the circuit illustrated in Fig. 1, hence the same reference characters are used in Fig. 2 to indicate parts therein corresponding to those in Fig. 1.

Referring now to Fig. 2, a supervisory circuit is associated with the incandescent lamp circuit and is operable to effect an operation of the audible signaling device herein represented as an annuciator or bell in the signaling circuit. The supervisory circuit, in the embodiment illustrated, comprises a transformer 40, the primary 4I of which is connected by conductors 42 and 43 to conductor I8 and conductor 5, respectively. It will be noted that the connections for transformer 4U as illustrated provide an uninterrupted path for the flow of current therethrough and Cil connect the primary 4I thereof in parallel with the alternatively operable legs of the incandescent lamp circuit. The transformer is a step down transformer having a ratio, for example, of 110/8 volts, depending on the voltage impressed on the service mains I9 and 20. The secondary' 44 of transformer 40 is connected through conductors 45 and 46 to a rectifier indicated generally at 41, which is preferably of the oxide type. The rectifier 41 serves to supply substantially 8 volt direct current through conductors 48 and 49 to a retarded or slow release relay 50. Convice with respect to the control of the electric lighting circuit by the signaling circuit to produce a visual signal is precisely-.the same as hereinbefore described in connection with the circuit :illustrated in Fig. l. However, with the addition of the supervisory circuit a failure of the lighting circuit to provide a visual signal does not render the device inoperative. Assume, for example, that a power failure occurs in the service mains I9 and 20, obviously there will be no power supplied to the transformer 40 and hence the supervisory circuit will be unenergized. Armature 53 of relay will, therefore, rest in contact with terminal 54 thereby connecting the bell 3| in the signalling circuit.

When the lighting circuit forming one element of my invention is unimpaired and the lamp I extinguished, the transformer 40 is energized, current flows through the rectifier 41 and rectified or direct current energizes relay 50 thereby maintaining an open circuit through the armature thereof. Should the signaling circuit be energized, relay 33 and in turn relay I4 will be actuated to open the normal lighting circuit to lamp I and to associate the lamp signaling circuit therewith. Due to the fact that the contacts of the current intermitting device 1 are normally spaced, the transformer remains energized. Current flowing through the device 1, as hereinbefore described, operates to make and break a direct circuit therethrough to lamp I, causing an intermittent illumination thereof When a direct circuit is made through the device 1 the transformer is shunted, hence, the normal operation of the device 1 effects a periodic energization of transformer 40. Relay 50, however, is preferably of the slow release type and is designed to maintain the armature in circuit opening position during the periodic intervals when the transformer 40 is unenergized. Obviously, should the transformer remain unenergized, for a longer period than the lag of the relay 50 permits, the armature 53 will contact with terminal 54 and connect the bell 3| in the signaling circuit. In other words the supervisory circuit only operates to sound an audible signal when a failure of the lamp signaling circuit occurs.

By tracing the circuit of the primary of the transformer 40. it will be noted that the lamp I is continuously in circuit therewith. Hence, if a in the signaling circuit. Under normal conditions when the lamp I is in circuit, the filament thereof serves to complete the primary circuit of the transformer with no illumination thereof. However when the lamp is illuminated as, for example, by an operation vof switch 4, the transformer is shunted thereby and becomes unenergized.

In conjunction with the foregoing described circuits, my invention contemplates the inclusion of a further automatic device for insuring the emission of an audiblesignaly in the vent of failure of the incandescent lamp signaling circuit. This device is illustrated in Fig. 3 wherein only a portion of the associated circuit is illustrated. The device indicated generally at 55 comprises elements substantially similar to those constituting the current intermitting device 1 except that the resistance element 56, coiled about the bimetallic element 51 thereof, has a substantially greater ohmic resistance, than that of the current intermitting device 1. Furthermore, the de- Cil (iii

vice 55 is preferably connected in parallel with device l as illustrated whereby it is normally partly shunted by the resistance element Il and wholly shunted by the bimetallic element 8 of the device 1. However, should the first device 'I remain open due to some mechanical failure thereof, current will not be shunted by the bimetallic element 8 of device l and hence the resistance element 55 of device 55 will continue to heat up until the bimetallic element 51 operates to close a circuittherethrough. 'I'his device 55 is also preferably designed to maintain a closed circuit therethrough during an interval of time sufficient to cause the supervisory circuit to connect the audible signalling device in the signaling circuit. Hence, upon a failure of the current, intermitting device to operate an audible signal is given, which incidentally indicates that the visual signaling circuit and associated controls therefor should be inspected.

In the foregoing description I have referred to a lnormal lighting circuit. This is to be understood as referring to the circuit established by relay I4 when unenergized. The lamp signaling circuit is that circuit established by the relay I4 when in its actuated position; and the lamp circuit comprises the normal lighting circuit and lamp 'signaling circuit.

Furthermore, it is to be understood that I do not wish to limit myself to the specific means set forth to accomplish the desired results, for it is evident that other suitable electrical means may be substituted for those illustrated and described. Likewise, variations in the specic circuit structures set forth may be made with resuits equally as emcacious as those attained in the associated circuits illustrated.

Hence, while I have illustrated circuits and associated means as the preferred embodiments of my invention and described the same in conjunction therewith, it is to be understood that the words which I have used are words of description and not of limitation and that changes within the purview of the appended claims may be made without departing' from the true scope and spirit of my invention in its broader aspects.

What I claim is:

1. In a telephone system, a first electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second electric circuit including a visual signaling device, means connected in said rst mentioned circuit and operable in response to an energization thereof for controlling said second circuit and means connected in series with said visual signaling device and operable upon a failure of current iiow therethrough to connect said audible signaling device in said iirst mentioned circuit.

2. In a telephone system, a first electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second electric circuit including a visual signaling device, means connected in said rst mentioned circuit and operable in response to an energization thereof for controlling said second circuit, means connected in series with said visual signaling device and operable upon a failure of current iiow therethrough to connect said audible signaling device in said first circuit, and means for maintaining said controlled second circuit for a predetermined interval of time.

3. In a. telephone system, a first electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second, electric lighting circuit including a visual signaling device, means connected in said rst mentioned circuit and operable in response to an energization thereof for controlling said second circuit, means connected in serieswith said visual signaling device and operable upon a failure of current ow therethrough to connect said audible signaling device in said first mentioned circuit and means for maintaining said controlled circuit after an initial energization of the first mentioned means.

4. In a telephone system, a first electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second, electric lighting circuit including a visual signaling device, means connected in said first mentioned circuit and operable in response to an energization thereof for controlling said second circuit, means connected in series with said visual signaling device and operable upon a failure of current flow therethrough to connect said audible signaling device in said first mentioned circuit, means for maintaining said controlled circuit after an initial energization of the first mentioned means, and means for opening said controlled circuit.

5. In a telephone system, a first electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second, electric lighting circuit including a visual signaling device, means connected in said first mentioned circuit and operable in response to an energization thereof for controlling said second circuit, means connected in series with said visual signaling device and operable upon a failure of current flow therethrough to connect said audible signaling device in said rst circuit, means for maintaining said controlled circuit'after an initial energization of the rst mentioned means and automatic means for limiting the time interval of control.

6. In a telephone system, a rst electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means comprising a current intermitting device connectible therein, means operable in response to an energlzation of said first circuit for connecting said current intermitting device in said second circuit and means connected in series with said visual signaling device and operable upon a failure of current iiow therethrough to connect said audible signaling device in said first circuit.

7. In a telephone system, a first electrical circuit comprising telephone trunk lines, a second, electric lighting circuit including a visual signaling device, a switch for controlling the same and a normally open shunt circuit around said switch, and means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit whereby a controlled operation of said visual signaling device is effected irrespective of the operating position of said switch.

8. In a telephone system, a first electrical circuit comprising telephone trunk lines, a second, electric lighting circuit including"a visual signaling device, a switch for controlling the same and a normally open shunt circuit around said switch, means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit whereby a controlled operation of said visual signaling device is effected irrespective of the operating position of said switch, and means for opening said shunt circuit.

9. In a telephone system, a first electrical circuit comprising telephone trunk lines, a second, electrical lighting circuit including a visual signaling device, a switch for controlling the same and a normally open shunt circuit around said switch, means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit whereby a controlled operation of said visual signaling device is effected irrespective of the operating position of said switch, and means for maintaining said shunt circuit after an initial energization of the rst mentioned means.

10. In a telephone system, a iirst electrical circuit comprising telephone trunk lines, a second electric lighting circuit including a visual signaling device, a switch for controlling the same and a normally open shunt circuit around said switch, means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit whereby a controlled operation of said visual signaling device is effected irrespective of the operating position of said switch, means for maintaining said shunt circuit after an initial energization of the first mentioned means, and means for discontinuing said maintained circuit.

11. In a telephone system, a rst electrical circuit comprising telephone trunk lines, a second, electric lighting circuit including a visual signaling device, a switch for controlling the same and a normally open shunt circuitaround said switch, means connected in said first mentioned circuit and operable in response to an energization thereof for opening' the circuit through said switch and closing said shunt circuit, means for maintaining said shunt circuit after an initial energization of the first mentioned means and automatic means for limiting the time interval of control.

12. In a. telephone system, a first electrical circuit comprising telephone trunk lines, a second, electric lighting circuit including an incandescent lamp, a switch for controlling the same and a normally open shunt circuit around said switch including an automatic current intermitting device and means connected in said rst mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit.

13. In a telephone system, a first electrical circuit comprising telephone trunk lines having an audible signaling device connectible therewith, a second, electric lighting circuit including a visual signaling device, .a switch for controlling the same and a normally! open shunt circuit around said switch, means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit. and means connected in said shunt circuit and operable upon a failure of current iiow therethrough to connect said audibie signaling device in said rst mentioned circuit.

14. In a telephone system, a first electrical circuit comprising truuk lines' having an audibie s :u =l a dcaice connectible therewith, a second, electric lighting circuit including a visual signaling device, a switch for controlling the same and a normally open shunt circuit around said switch including a'. current responsive means operable to connect said audible signaling device in said first mentioned circuit and means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit whereby said current responsive means is connected in series with said visual signaling device and operates upon a failure of current flow therethrough to connect said audible signaling device in said first mentioned circuit.

15. In a telephone system, a first electrical circuit comprising trunk lines having an audible signaling device connectible therewith, an incandescent lamp, a normal lighting circuit therefor and a control circuit connectible therewith, means connected in said rst mentioned circuit and operable in response to an energization thereof for interrupting said normal lighting circuit and closing said control circuit and means connected in said control circuit and operable upon a failure of current flow therethrough to connect said audible signaling device in said first circuit. f

16. In a telephone system, a rst electrical circuit comprising trunk lines having an audible signaling device connectible therewith, an incandescent lamp, a normal lighting circuit therefor and a control circuit connectible therewith, means connected in said first mentioned circuit and operable in response to an energization thereof for interrupting said normal lighting circuit and closing said control circuit and a supervisory circuit inductively coupled with said control circuit including means operable upon a failure of current flow therethrough to connect said audiblev signaling device in said first mentioned circuit.

17. In a telephone system, a first electrical circuit comprising trunk lines having an audible signaling device connectible therewith, an incandescent lamp, a normal lighting circuit there-V for and a control circuit connectible therewith including a current intermitting device, means connected in said first mentioned circuit and operable in response to an energization thereof for opening said normal circuit and closing said control circuit and means connected in said control circuit and operable upon a failure of current flow therethrough to connect said audible signaling device in said first mentioned circuit.

18. In a telephone system, a first electrical circuit comprising telephone trunk lines hav- Y ing an audible signaling device connectible therewith, a second electric circuit including a visual 

